OpenE2K/qemu-e2k
13
4
Fork 0
Code Issues 4 Pull Requests Projects 2 Releases Activity

util: add cacheinfo

Browse Source 
Add helpers to gather cache info from the host at init-time.

For now, only export the host's I/D cache line sizes, which we
will use to improve cache locality to avoid false sharing.

Suggested-by: Richard Henderson <rth@twiddle.net>
Suggested-by: Geert Martin Ijewski <gm.ijewski@web.de>
Tested-by:    Geert Martin Ijewski <gm.ijewski@web.de>
Signed-off-by: Emilio G. Cota <cota@braap.org>
Message-Id: <1496794624-4083-1-git-send-email-cota@braap.org>
[rth: Move all implementations from tcg/ppc/]
Signed-off-by: Richard Henderson <rth@twiddle.net>
This commit is contained in:
Emilio G. Cota 2017-06-06 20:17:04 -04:00 committed by Richard Henderson
parent cef8fd6836
commit b255b2c8a5
4 changed files with 191 additions and 69 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
include/qemu/osdep.h
View File

@ -483,4 +483,7 @@ char *qemu_get_pid_name(pid_t pid);
*/
pid_t qemu_fork(Error **errp);
extern int qemu_icache_linesize;
extern int qemu_dcache_linesize;
#endif

71
tcg/ppc/tcg-target.inc.c
View File

@ -2820,14 +2820,11 @@ void tcg_register_jit(void *buf, size_t buf_size)
}
#endif /* __ELF__ */
static size_t dcache_bsize = 16;
static size_t icache_bsize = 16;
void flush_icache_range(uintptr_t start, uintptr_t stop)
{
uintptr_t p, start1, stop1;
size_t dsize = dcache_bsize;
size_t isize = icache_bsize;
size_t dsize = qemu_dcache_linesize;
size_t isize = qemu_icache_linesize;
start1 = start & ~(dsize - 1);
stop1 = (stop + dsize - 1) & ~(dsize - 1);
@ -2844,67 +2841,3 @@ void flush_icache_range(uintptr_t start, uintptr_t stop)
asm volatile ("sync" : : : "memory");
asm volatile ("isync" : : : "memory");
}
#if defined _AIX
#include <sys/systemcfg.h>
static void __attribute__((constructor)) tcg_cache_init(void)
{
icache_bsize = _system_configuration.icache_line;
dcache_bsize = _system_configuration.dcache_line;
}
#elif defined __linux__
static void __attribute__((constructor)) tcg_cache_init(void)
{
unsigned long dsize = qemu_getauxval(AT_DCACHEBSIZE);
unsigned long isize = qemu_getauxval(AT_ICACHEBSIZE);
if (dsize == 0 || isize == 0) {
if (dsize == 0) {
fprintf(stderr, "getauxval AT_DCACHEBSIZE failed\n");
}
if (isize == 0) {
fprintf(stderr, "getauxval AT_ICACHEBSIZE failed\n");
}
exit(1);
}
dcache_bsize = dsize;
icache_bsize = isize;
}
#elif defined __APPLE__
#include <sys/sysctl.h>
static void __attribute__((constructor)) tcg_cache_init(void)
{
size_t len;
unsigned cacheline;
int name[2] = { CTL_HW, HW_CACHELINE };
len = sizeof(cacheline);
if (sysctl(name, 2, &cacheline, &len, NULL, 0)) {
perror("sysctl CTL_HW HW_CACHELINE failed");
exit(1);
}
dcache_bsize = cacheline;
icache_bsize = cacheline;
}
#elif defined(__FreeBSD__) || defined(__FreeBSD_kernel__)
#include <sys/sysctl.h>
static void __attribute__((constructor)) tcg_cache_init(void)
{
size_t len = 4;
unsigned cacheline;
if (sysctlbyname ("machdep.cacheline_size", &cacheline, &len, NULL, 0)) {
fprintf(stderr, "sysctlbyname machdep.cacheline_size failed: %s\n",
strerror(errno));
exit(1);
}
dcache_bsize = cacheline;
icache_bsize = cacheline;
}
#endif

1
util/Makefile.objs
View File

@ -20,6 +20,7 @@ util-obj-y += host-utils.o
util-obj-y += bitmap.o bitops.o hbitmap.o
util-obj-y += fifo8.o
util-obj-y += acl.o
util-obj-y += cacheinfo.o
util-obj-y += error.o qemu-error.o
util-obj-y += id.o
util-obj-y += iov.o qemu-config.o qemu-sockets.o uri.o notify.o

185
util/cacheinfo.c Normal file
View File

@ -0,0 +1,185 @@
/*
* cacheinfo.c - helpers to query the host about its caches
*
* Copyright (C) 2017, Emilio G. Cota <cota@braap.org>
* License: GNU GPL, version 2 or later.
* See the COPYING file in the top-level directory.
*/
#include "qemu/osdep.h"
int qemu_icache_linesize = 0;
int qemu_dcache_linesize = 0;
/*
* Operating system specific detection mechanisms.
*/
#if defined(_AIX)
# include <sys/systemcfg.h>
static void sys_cache_info(int *isize, int *dsize)
{
*isize = _system_configuration.icache_line;
*dsize = _system_configuration.dcache_line;
}
#elif defined(_WIN32)
static void sys_cache_info(int *isize, int *dsize)
{
SYSTEM_LOGICAL_PROCESSOR_INFORMATION *buf;
DWORD size = 0;
BOOL success;
size_t i, n;
/* Check for the required buffer size first. Note that if the zero
size we use for the probe results in success, then there is no
data available; fail in that case. */
success = GetLogicalProcessorInformation(0, &size);
if (success || GetLastError() != ERROR_INSUFFICIENT_BUFFER) {
return;
}
n = size / sizeof(SYSTEM_LOGICAL_PROCESSOR_INFORMATION);
size = n * sizeof(SYSTEM_LOGICAL_PROCESSOR_INFORMATION);
buf = g_new0(SYSTEM_LOGICAL_PROCESSOR_INFORMATION, n);
if (!GetLogicalProcessorInformation(buf, &size)) {
goto fail;
}
for (i = 0; i < n; i++) {
if (buf[i].Relationship == RelationCache
&& buf[i].Cache.Level == 1) {
switch (buf[i].Cache.Type) {
case CacheUnified:
*isize = *dsize = buf[i].Cache.LineSize;
break;
case CacheInstruction:
*isize = buf[i].Cache.LineSize;
break;
case CacheData:
*dsize = buf[i].Cache.LineSize;
break;
default:
break;
}
}
}
fail:
g_free(buf);
}
#elif defined(__APPLE__) \
|| defined(__FreeBSD__) || defined(__FreeBSD_kernel__)
# include <sys/sysctl.h>
# if defined(__APPLE__)
# define SYSCTL_CACHELINE_NAME "hw.cachelinesize"
# else
# define SYSCTL_CACHELINE_NAME "machdep.cacheline_size"
# endif
static void sys_cache_info(int *isize, int *dsize)
{
/* There's only a single sysctl for both I/D cache line sizes. */
long size;
size_t len = sizeof(size);
if (!sysctlbyname(SYSCTL_CACHELINE_NAME, &size, &len, NULL, 0)) {
*isize = *dsize = size;
}
}
#else
/* POSIX */
static void sys_cache_info(int *isize, int *dsize)
{
# ifdef _SC_LEVEL1_ICACHE_LINESIZE
*isize = sysconf(_SC_LEVEL1_ICACHE_LINESIZE);
# endif
# ifdef _SC_LEVEL1_DCACHE_LINESIZE
*dsize = sysconf(_SC_LEVEL1_DCACHE_LINESIZE);
# endif
}
#endif /* sys_cache_info */
/*
* Architecture (+ OS) specific detection mechanisms.
*/
#if defined(__aarch64__)
static void arch_cache_info(int *isize, int *dsize)
{
if (*isize == 0 || *dsize == 0) {
unsigned ctr;
/* The real cache geometry is in CCSIDR_EL1/CLIDR_EL1/CSSELR_EL1,
but (at least under Linux) these are marked protected by the
kernel. However, CTR_EL0 contains the minimum linesize in the
entire hierarchy, and is used by userspace cache flushing. */
asm volatile("mrs\t%0, ctr_el0" : "=r"(ctr));
if (*isize == 0) {
*isize = 4 << (ctr & 0xf);
}
if (*dsize == 0) {
*dsize = 4 << ((ctr >> 16) & 0xf);
}
}
}
#elif defined(_ARCH_PPC) && defined(__linux__)
static void arch_cache_info(int *isize, int *dsize)
{
if (*isize == 0) {
*isize = qemu_getauxval(AT_ICACHEBSIZE);
}
if (*dsize == 0) {
*dsize = qemu_getauxval(AT_DCACHEBSIZE);
}
}
#else
static void arch_cache_info(int *isize, int *dsize) { }
#endif /* arch_cache_info */
/*
* ... and if all else fails ...
*/
static void fallback_cache_info(int *isize, int *dsize)
{
/* If we can only find one of the two, assume they're the same. */
if (*isize) {
if (*dsize) {
/* Success! */
} else {
*dsize = *isize;
}
} else if (*dsize) {
*isize = *dsize;
} else {
#if defined(_ARCH_PPC)
/* For PPC, we're going to use the icache size computed for
flush_icache_range. Which means that we must use the
architecture minimum. */
*isize = *dsize = 16;
#else
/* Otherwise, 64 bytes is not uncommon. */
*isize = *dsize = 64;
#endif
}
}
static void __attribute__((constructor)) init_cache_info(void)
{
int isize = 0, dsize = 0;
sys_cache_info(&isize, &dsize);
arch_cache_info(&isize, &dsize);
fallback_cache_info(&isize, &dsize);
qemu_icache_linesize = isize;
qemu_dcache_linesize = dsize;
}